The present invention relates to a liquid crystal display (LCD) device that drives a liquid crystal panel and, in particular, to a technique that is effectively applicable to an LCD-driving large scale integration (LSI) (large-scale semiconductor integrated circuit) including a driver circuit that dives signal lines to the liquid crystal display panel by AC voltage.
Lately, a dot matrix type liquid crystal panel in which a plurality of display pixels are arranged in a two-dimensional array, for example, in a matrix is generally used as a display device of portable electronic devices such as mobile phones and Personal Digital Assistants. Inside these devices, a display control device implemented in a semiconductor integrated circuit for performing display control of this liquid crystal panel and a driver circuit for driving the liquid crystal panel or the display control device including such driver circuit are installed.
The internal circuit of such display control device implemented in a semiconductor integrated circuit can operate on a low voltage of 5 V or less, whereas a high voltage such as 5-40 V is required to drive the display of the liquid crystal panel. For this reason, in the display control device, a driver circuit and an output circuit which operate on a voltage boosted from a supply voltage are provided and a level shifter circuit is provided between the internal logic operating on a voltage of 5 V or less and the driver circuit operating on the boosted voltage.
Because continuous application of DC voltage to liquid crystal deteriorates the liquid crystal, a liquid crystal panel driver must drive the panel by AC voltage. For such driving by AC voltage, there exists a liquid crystal driver circuit in which an amplifier operating on a positive supply voltage and an amplifier operating on a negative supply voltage are provided for each output terminal, adapted to output an AC drive signal by alternately connecting the positive and negative amplifiers to one output terminal. As an invention relating to the thus configured liquid crystal driver circuit, there exits the one described, for example, in patent document 1.    [Patent document 1] Japanese Unexamined Patent Publication No. Hei 10(1998)-062744